Axle suspension for rigid axles of vehicles

ABSTRACT

An axle suspension for rigid axles of vehicles, especially air-cushioned utility vehicles, with: a twistable four-point connecting rod ( 4 ), which is connected above the said vehicle axle ( 3 ) to the said vehicle axle ( 3 ). The twistable four-point connecting rod ( 4 ) is connected to the vehicle body ( 1, 2 ), on the other hand, via two said joints ( 5, 6, 7, 8 ) each, which are arranged at spaced locations from one another in the longitudinal direction of the vehicle. At least one spring assembly unit ( 19, 20 ) per vehicle side is located for springing between the said vehicle axle ( 3 ) and the said vehicle body ( 1, 2 ). A axle strut ( 21 ) for axle guiding, extends approximately in the middle of the vehicle in the longitudinal direction of the vehicle and connects the said vehicle axle ( 3 ) to the said vehicle body ( 1, 2 ) in a vertically movable manner.

[0001] The present invention pertains to an axle suspension for rigidaxles of vehicles, especially of air-cushioned utility vehicles.

[0002] Axle suspensions that contain a four-point connecting rod havebeen known, e.g., from DE 195 21 874 A1. The design embodiment of suchaxle suspensions is, in principle, simple, compact and cost-saving andhas proved to be definitely successful in practice. However, this axlesuspension, like other designs known from the state of the art, has thedrawback that numerous components are necessary for axle guiding, whichrequires an increased assembly effort and also adversely affects theoverall weight of the vehicle. Furthermore, prior-art axle suspensionsare sometimes kinematically redundant. This in turn leads to anundefined course of kinematic processes within the axle construction incertain situations, which has an adverse effect on the coordination ofthe chassis or the chassis dynamics in the vertical and lateraldirections under certain circumstances.

[0003] The technical object of the present invention is to improve anaxle suspension such that the kinematic conditions are improved in orderto optimize the dynamics of the vehicle movement. Moreover, the numberof the individual components shall be further reduced.

[0004] This object is accomplished by the features of patent claim 1.Thus, an axle suspension according to the present invention comprises atwistable four-point connecting rod, which is arranged above the vehicleaxle and is connected to the vehicle axle, on the one hand, and to thevehicle body, on the other hand, via two joints located at spacedlocations from one another in the transverse direction of the vehicle.

[0005] In addition, at least one spring assembly unit is arrangedbetween the vehicle axle and the vehicle body on each side of thevehicle.

[0006] The fact that only one axle strut, which extends in thelongitudinal direction approximately in the middle of the vehicle andconnects the vehicle axle to the vehicle body in a vertically movablemanner, is used, can be considered to be the peculiar feature of such anaxle suspension. The axle strut is arranged on the side of the vehicleaxle located opposite the four-point connecting rod. The mounting of thefour-point connecting rod and the axle strut in the reverse arrangementis, of course, within the scope of the present invention.

[0007] The kinematic conditions of the axle suspension are simplifiedand optimized by such a design. The number of components decreasesconsiderably, so that the axle structure as a whole is less expensivethan designs known hitherto.

[0008] Special embodiments of the subject of the present invention alsoappear from the features of the subclaims.

[0009] Thus, the spring assembly units or the shock absorbers aremounted according to the present invention on longitudinal beams, whichin turn have a connection to the vehicle axle, so that there is anindirect connection between the vehicle axle and the vehicle body. Ithas proved to be particularly advantageous for each longitudinal beam tohave at least one mount for the spring assembly units. The longitudinalbeams are now arranged extending on each side of the vehicleapproximately in the longitudinal direction of the vehicle and mayaccommodate one or more spring assembly units as well as also shockabsorbers if necessary. For mounting the spring assembly units and theshock absorbers, the mounts may be designed as joints, andball-and-socket joints may also be used for this purpose according to aspecial embodiment of the present invention. The said ball-and-socketjoints have the advantage of ensuring an easily movable mounting of thecorresponding assembly units, so that the pneumatic spring bellows areloaded to an extremely low extent only, e.g., in the case of the use ofpneumatic springs.

[0010] The components of the vehicle body include according to thepresent invention at least two parallel longitudinal frames, which areconnected to one another by crossbeams located at spaced locations fromone another approximately in the transverse direction of the vehicle.

[0011] The axle strut for axle guiding, which extends in thelongitudinal direction of the vehicle approximately in the middle of thevehicle and connects the vehicle axle to the vehicle body in avertically movable manner, may be connected to one of the crossbeams bymeans of a carrier bracket in another embodiment of the presentinvention. Quite generally, a carrier bracket is defined as a mountingdevice, which accommodates a molecular joint of the axle strut, on theone hand, and is fixed to the vehicle body, on the other hand. The axlestrut preferably has a molecular joint at each of its ends.

[0012] To achieve optimal springing of the vehicle axle, the springassembly unit may be arranged in front of or behind the vehicle axle orin front or and behind the vehicle axle in an axle suspension accordingto the present invention.

[0013] Exemplary embodiments of the subject of the present inventionwill be explained in greater detail below on the basis of the drawingsattached. In the drawings,

[0014]FIG. 1 shows a perspective view of an exemplary embodiment of theaxle suspension according to the present invention as viewed obliquelyfrom the front, i.e., opposite the direction of travel of the vehicle,

[0015]FIG. 2 shows a perspective view as viewed obliquely from the rear,i.e., in the direction of travel of the vehicle,

[0016]FIG. 3 shows a side view of the axle suspension according to thepresent invention without the vehicle wheel that is the right-hand wheelin the direction of travel,

[0017]FIG. 4 shows a sectional view of a molecular joint used for theaxle suspension according to the present invention, and

[0018]FIG. 5 shows a top view of an axle suspension according to thepresent invention.

[0019]FIGS. 1 through 3 show the axle suspension according to thepresent invention on a utility vehicle chassis, not shown here, which isprovided with longitudinal frames 1 a, 1 b. The longitudinal frames 1 aand 1 b are arranged at laterally spaced locations from one another andare firmly connected to one another by the crossbeams 2 a, 2 b. Thelongitudinal frames 1 a, 1 b and the crossbeams 2 a, 2 b are parts ofthe vehicle body 1, 2. The vehicle axle 3, which is connected to thelongitudinal frames 1 a, 1 b and to one of the crossbeams 2 b via afour-point connecting rod 4, is located under the longitudinal frames 1a and 1 b. Furthermore, the vehicle wheels 15 and 16 are fastened to thevehicle axle 3. The four-point connecting rod 4 has a total of fourjoints 5, 6, 7 and 8, with two joints 6, 8 each being fastened, as wasdescribed above, to the vehicle frame and two joints 5, 7 to the vehicleaxle. The joints fastened to the vehicle axle and to the vehicle frameare arranged at spaced locations from one another in the transversedirection of the vehicle and are designed as molecular joints.

[0020] A molecular joint is, in principle, a joint as it is shown as anexample as a ball-and-socket joint in FIG. 4. The molecular jointcomprises here an inner joint ball 30, a housing 32 surrounding thejoint ball as well as an elastomer 31 arranged between the joint ball 30and the housing 32. In the exemplary embodiment according to FIG. 4, thejoint ball 30 has a two-part design, consisting of an inner, metallicjoint axis 33 and an outer ball 34 made in one piece with it from anelastomer. Other embodiments of a molecular joint may be a joint ball 30made entirely of metal or have a cylindrical inner part instead of aball. Such molecular joints can be correspondingly adapted to the loadsacting on the joint by selecting the elastomer arranged between thejoint ball 30 and the housing 32. In addition, recesses, which affectthe characteristics of the joint in a specific manner, may be providedat least in some areas within the elastomer and/or the housing or on theinner part of the joint. For example, molecular joints may have a lowerdamping in one direction and a correspondingly greater damping in atleast one direction that is offset in relation to that direction.

[0021] The views in FIGS. 1 through 3 also show that the vehicle axle 3has a connection to a crossbeam 2 b, which is formed by an axle strut21, which is in turn mounted in a carrier bracket 10 on one side. Thisaxle strut contains one molecular joint 13, 14 on each side, themolecular joint 13 being articulated under the vehicle axle 3 and themolecular joint 14 being accommodated in the carrier bracket 10. Themolecular joints 5, 6, 7, 8, 13, and 14 have, in principle, theabove-described design and make it possible to absorb both longitudinalas well as vertical forces and angulations (cardanics), which are causedby the movements of the vehicle axle 3. Redundancy of the kinematicdegrees of freedom is prevented by the use of the molecular joints, sothat a more optimal forward coordination can be brought about in termsof the dynamics of the chassis in the vertical and lateral directions.

[0022] A longitudinal beam 11 and 12 each is fastened to the vehicleaxle 3 on each side of the vehicle for the indirect connection of thevehicle axle to the vehicle body 1, 2. In the embodiment being shown,these longitudinal beams 11, 12 establish the said connection to thevehicle body 1, 2 via a spring assembly unit 19, 20 each or a shockabsorber 35, 36 each.

[0023] Respective mounts 17 a, 17 b and 18 a, 18 b are present on thelongitudinal beams 11 and 12 for mounting the spring assembly units 19,20 and the shock absorbers 35, 36, respectively.

[0024] This leads to a reduction in the number of the components usuallyused in prior-art axle designs and thus reduces the amount of parts tobe stocked and the assembly times for the axle design according to thepresent invention.

[0025] The top view of an exemplary embodiment of the axle designaccording to the present invention in FIG. 5 shows the position of thefour-point connecting rod 4 as well as its articulation points on thebody and on the vehicle axle 3.

[0026] It is, of course, possible to arrange three, four or more suchspring elements instead of the two spring assembly units shown in anaxle suspension according to the present invention and to arrange thespring assembly units 19, 20 in front of or behind the vehicle axle 3when viewed in the direction of travel.

LIST OF REFERENCE NUMBERS

[0027]1 a Longitudinal frame

[0028]1 b Longitudinal frame

[0029]2 a Crossbeam

[0030]2 b Crossbeam

[0031]3 Vehicle axle

[0032]4 Four-point connecting rod

[0033]5 Joint

[0034]6 Joint

[0035]7 Joint

[0036]8 Joint

[0037]10 Carrier bracket

[0038]11 Longitudinal beam

[0039]12 Longitudinal beam

[0040]13 Molecular joint

[0041]14 Molecular joint

[0042]15 Vehicle wheel

[0043]16 Vehicle wheel

[0044]17 a Mount

[0045]17 b Mount

[0046]18 a Mount

[0047]18 b Mount

[0048]19 Spring assembly unit

[0049]20 Spring assembly unit

[0050]21 Axle strut

[0051]30 Joint ball

[0052]31 Elastomer

[0053]32 Housing

[0054]33 Joint axis

[0055]34 Outer ball

[0056]35 Shock absorber

[0057]36 Shock absorber

1. Axle suspension for rigid axles of vehicles, especially air-cushionedutility vehicles, with: a said twistable four-point connecting rod (4),which is connected above the said vehicle axle (3) to the said vehicleaxle (3), on the one hand, and to the said vehicle body (1, 2), on theother hand, via two said joints (5, 6, 7, 8) each, which are arranged atspaced locations from one another in the longitudinal direction of thevehicle, at least one said spring assembly unit (19, 20) per vehicleside, which is located for springing between the said vehicle axle (3)and the said vehicle body (1, 2), and a said axle strut (21) for axleguiding, which extends approximately in the middle of the vehicle in thelongitudinal direction of the vehicle and connects the said vehicle axle(3) to the said vehicle body (1, 2) in a vertically movable manner. 2.Axle suspension in accordance with claim 1, characterized in that thesaid longitudinal beams (11, 12) arranged on the said vehicle axle (3)have at least one said mount (17, 18) each for the said spring assemblyunits (19, 20) or said shock absorbers (35, 36).
 3. Axle suspension inaccordance with claim 2, characterized in that the said mounts (17, 18)for the said spring assembly units (19, 20) or for the said shockabsorbers (35, 36) are designed as joints.
 4. Axle suspension inaccordance with claim 3, characterized in that the joints areball-and-socket joints.
 5. Axle suspension in accordance with one of theabove claims, characterized in that the said vehicle body (1, 2) has twosaid parallel longitudinal frames (1 a, 1 b) and said crossbeams (2 a, 2b), which connect the said longitudinal beams approximately in thetransverse direction of the vehicle and are arranged at spaced locationsfrom one another.
 6. Axle suspension in accordance with claim 5,characterized in that the said axle strut (21) having said molecularjoints (13, 14) on both sides is connected to a said crossbeam (2 a or 2b) on the side of the said vehicle axle (3) located opposite the saidfour-point connecting rod (4), on the one hand, and via a said supportbracket (10), on the other hand.
 7. Axle suspension in accordance withone of the above claims, characterized in that the said spring assemblyunit (19, 20) is arranged in front of or behind the said vehicle axle(3).
 8. Axle suspension in accordance with one of the claims 1 through6, characterized in that a said spring assembly unit (19, 20) each isarranged in front of and behind the said vehicle axle (3).